The story is told by Nick Carraway, a man who moves to Long Island, New York, from the Midwest. Nick is not rich but he lives in a rich area that has two towns called 'East Egg' and 'West Egg'. The 'old rich' live in East Egg, while the 'New Rich' reside in West Egg. Nick lives in a small house in West Egg. Nick's next-door neighbor is Jay Gatsby. Jay is in love with Nick's cousin, Daisy. But, Daisy is married to a man named Tom. The novel is about Jay and his hope that he can steal Daisy from Tom.

The events of the novel happen in the summer of 1922. Nick Carraway, a man who grew up in the American Midwest, is the narrator. He moves to New York, to be a bonds salesman. There, he rents a house in the small human community of West Egg. The person living next to him is Jay Gatsby, a mysterious man who also has a lot of money. Jay Gatsby also hosts many expensive parties frequently. Yet, he never participates in his own parties. Nick drives out to visit his cousin Daisy in East Egg. There, he meets her husband, Tom Buchanan. He is also introduced to her friend, Jordan Baker. Nick learns from her that Tom has been having an affair with Myrtle Wilson. Nick decides to hold his judgment.

Later in the summer, Nick is invited to one of Gatsby's parties. There, he meets Gatsby himself, a young and charming man. Nick learns that Gatsby was once in a romantic relationship with Daisy, many years ago. Gatsby is still in love with her, and spends many nights looking at the green light from Daisy's dock across his mansion. He is hoping that he could impress Daisy with his rich lifestyle and wild parties. Gatsby asks Nick to arrange for Daisy and him to meet. Nick invites them both over for tea, and they begin to fall in love again. They then start an affair with one another.

After a short time, Tom notices that Daisy and Gatsby are in love. The group meets at a hotel, where Daisy is forced to choose between Gatsby and Tom. She chooses Tom, and the group begins to drive home. Along the way, Daisy, driving Gatsby's car, accidentally hits and kills Myrtle. Gatsby tells Nick that he will take the blame in order to save Daisy. Later, he is then shot dead by Myrtle's husband, George, believing that Gatsby was the one responsible. George then kills himself.

Nick holds a funeral for Gatsby, but few people show up. Upset at everyone, and all the events that have happened, Nick moves back to the Midwest.